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  <div class="section" id="cdap">
<span id="faqs-cdap"></span><h1>常见问题: CDAP<a class="headerlink" href="#cdap" title="Permalink to this headline">🔗</a></h1>
<p class="rubric">Configuration: General</p>
<div class="section" id="what-are-the-memory-and-core-requirements-for-cdap">
<span id="faq-installation-startup-memory-core-requirements"></span><h2>What are the memory and core requirements for CDAP?<a class="headerlink" href="#what-are-the-memory-and-core-requirements-for-cdap" title="Permalink to this headline">🔗</a></h2>
<p>The requirements are governed by two sources: CDAP and YARN, and the requirements are
<a class="reference external" href="../../admin-manual/system-requirements.html#admin-manual-memory-core-requirements" title="(in Cask Data Application Platform v6.1.1)"><span class="xref std std-ref">described here</span></a>.</p>
</div>
<div class="section" id="how-do-i-set-the-cdap-properties-for-components-running-on-multiple-machines">
<h2>How do I set the CDAP properties for components running on multiple machines?<a class="headerlink" href="#how-do-i-set-the-cdap-properties-for-components-running-on-multiple-machines" title="Permalink to this headline">🔗</a></h2>
<p>In the configuration file <code class="docutils literal notranslate"><span class="pre">cdap-site.xml</span></code>, there are numerous properties that specify an
IP address where a service is running, such as <code class="docutils literal notranslate"><span class="pre">router.server.address</span></code>,
<code class="docutils literal notranslate"><span class="pre">data.tx.bind.address</span></code>, <code class="docutils literal notranslate"><span class="pre">app.bind.address</span></code>, <code class="docutils literal notranslate"><span class="pre">router.bind.address</span></code>.</p>
<p>Our convention is that:</p>
<ul class="simple">
<li><em>*.bind.*</em> properties are what services use during startup to listen on a particular interface/port.</li>
<li><em>*.server.*</em> properties are used by clients to connect to another (potentially remote) service.</li>
</ul>
<p>For <em>*.bind.address</em> properties, it is often easiest just to set these to <code class="docutils literal notranslate"><span class="pre">'0.0.0.0'</span></code>
to listen on all interfaces.</p>
<p>The <em>*.server.*</em> properties are used by clients to connect to another remote service.
The only one you should need to configure initially is <code class="docutils literal notranslate"><span class="pre">router.server.address</span></code>, which is
used by the UI to connect to the router.  As an example, ideally routers running in
production would have a load balancer in front, which is what you would set
<code class="docutils literal notranslate"><span class="pre">router.server.address</span></code> to. Alternatively, you could configure each UI instance to point
to a particular router, and if you have both UI and router running on each node, you could
use <code class="docutils literal notranslate"><span class="pre">'127.0.0.1'</span></code>.</p>
</div>
<div class="section" id="how-do-i-use-yarn-with-the-linux-container-executor">
<h2>How do I use YARN with the Linux Container Executor?<a class="headerlink" href="#how-do-i-use-yarn-with-the-linux-container-executor" title="Permalink to this headline">🔗</a></h2>
<p>If you have YARN configured to use <code class="docutils literal notranslate"><span class="pre">LinuxContainerExecutor</span></code> (see the setting for
<code class="docutils literal notranslate"><span class="pre">yarn.nodemanager.container-executor.class</span></code>):</p>
<ul>
<li><p class="first">The <code class="docutils literal notranslate"><span class="pre">cdap</span></code> user needs to be present on all Hadoop nodes.</p>
</li>
<li><p class="first">When using a <code class="docutils literal notranslate"><span class="pre">LinuxContainerExecutor</span></code>, if the UID for the <code class="docutils literal notranslate"><span class="pre">cdap</span></code> user is less than
500, you will need to add the <code class="docutils literal notranslate"><span class="pre">cdap</span></code> user to the allowed users configuration for the
<code class="docutils literal notranslate"><span class="pre">LinuxContainerExecutor</span></code> in YARN by editing the <code class="docutils literal notranslate"><span class="pre">/etc/hadoop/conf/container-executor.cfg</span></code>
file. Change the line for <code class="docutils literal notranslate"><span class="pre">allowed.system.users</span></code> to:</p>
<div class="highlight-console notranslate"><div class="highlight"><pre><span></span><span class="go">allowed.system.users=cdap</span>
</pre></div>
</div>
</li>
</ul>
</div>
<div class="section" id="where-is-the-cdap-cli-command-line-interface-in-distributed-mode">
<h2>Where is the CDAP CLI (Command Line Interface) in Distributed mode?<a class="headerlink" href="#where-is-the-cdap-cli-command-line-interface-in-distributed-mode" title="Permalink to this headline">🔗</a></h2>
<p>If you’ve installed the <code class="docutils literal notranslate"><span class="pre">cdap-cli</span></code> RPM or DEB, it’s located under <code class="docutils literal notranslate"><span class="pre">/opt/cdap/cli/bin</span></code>.
If you have installed CDAP manually (without using Cloudera Manager or Apache Ambari),
you can add this location to your PATH to prevent the need for specifying the entire script every time.</p>
<p><strong>Note:</strong> These commands will list the contents of the package <code class="docutils literal notranslate"><span class="pre">cdap-cli</span></code>, once it has
been installed:</p>
<div class="highlight-console notranslate"><div class="highlight"><pre><span></span><span class="gp">$</span> rpm -ql cdap-cli
<span class="gp">$</span> dpkg -L cdap-cli
</pre></div>
</div>
<p class="rubric">Installation: YARN</p>
</div>
<div class="section" id="i-ve-followed-the-install-instructions-yet-cdap-does-not-start-what-next">
<h2>I’ve followed the install instructions, yet CDAP does not start. What next?<a class="headerlink" href="#i-ve-followed-the-install-instructions-yet-cdap-does-not-start-what-next" title="Permalink to this headline">🔗</a></h2>
<p>If you have followed <a class="reference external" href="../../admin-manual/installation/index.html#installation-index" title="(in Cask Data Application Platform v6.1.1)"><span class="xref std std-ref">the installation instructions</span></a>, and CDAP either did not startup, check:</p>
<ul>
<li><p class="first">Look in the CDAP logs for error messages (located either in <code class="docutils literal notranslate"><span class="pre">/var/log/cdap</span></code> for Distributed CDAP or
<code class="docutils literal notranslate"><span class="pre">$CDAP_HOME/logs</span></code> for CDAP Sandbox)</p>
</li>
<li><p class="first">If you see an error such as:</p>
<div class="highlight-console notranslate"><div class="highlight"><pre><span></span><span class="go">ERROR [main:c.c.c.StandaloneMain@268] - Failed to start CDAP Sandbox</span>
<span class="go">java.lang.NoSuchMethodError:</span>
<span class="go">io.cdap.cdap.UserInterfaceService.getServiceName()Ljava/lang/String</span>
</pre></div>
</div>
<p>then you have downloaded the CDAP Sandbox version of CDAP, which is not intended
to be run on Hadoop clusters. Download the appropriate distributed packages (RPM or
Debian version) from <a class="reference external" href="http://cask.co/downloads">http://cask.co/downloads</a>.</p>
</li>
<li><p class="first">Check permissions of directories:</p>
<ul class="simple">
<li>The <a class="reference external" href="../../admin-manual/installation/packages.html#packages-configuration-options" title="(in Cask Data Application Platform v6.1.1)"><span class="xref std std-ref">CDAP HDFS User</span></a> (by default, <code class="docutils literal notranslate"><span class="pre">yarn</span></code>) owns the HDFS directory (by default,  <code class="docutils literal notranslate"><span class="pre">/cdap</span></code>).</li>
<li>The <a class="reference external" href="../../admin-manual/installation/packages.html#packages-configuration-options" title="(in Cask Data Application Platform v6.1.1)"><span class="xref std std-ref">Kafka Log directory</span></a> (by default, <code class="docutils literal notranslate"><span class="pre">/data/cdap/kafka-logs</span></code>),
must be writable by the CDAP UNIX user.</li>
<li>The <a class="reference external" href="../../admin-manual/installation/packages.html#packages-configuration-tmp-files" title="(in Cask Data Application Platform v6.1.1)"><span class="xref std std-ref">temp directories</span></a> utilized by CDAP must be writable by the CDAP UNIX user.</li>
</ul>
</li>
</ul>
<ul>
<li><p class="first">Check YARN using the YARN Resource Manager UI and see if the CDAP Master services are starting up.
Log into the cluster at <code class="docutils literal notranslate"><span class="pre">http://&lt;host&gt;:8088/cluster/apps/RUNNING</span></code>. The CDAP Master
services should be listed under “RUNNING”:</p>
<a class="reference internal image-reference" href="_images/yarn-rm-running.png"><img alt="_images/yarn-rm-running.png" class="align-center" src="_images/yarn-rm-running.png" style="width: 8in;" /></a>
</li>
</ul>
<ul>
<li><p class="first">If CDAP Master has started, query the backend by using a command (substituting for <code class="docutils literal notranslate"><span class="pre">&lt;host&gt;</span></code> as appropriate):</p>
<div class="highlight-console notranslate"><div class="highlight"><pre><span></span><span class="gp">$</span> curl -w<span class="s1">&#39;\n&#39;</span> &lt;host&gt;:11015/v3/system/services/status
</pre></div>
</div>
<p>The response should be something similar to:</p>
<div class="highlight-console notranslate"><div class="highlight"><pre><span></span><span class="go">{&quot;dataset.executor&quot;:&quot;OK&quot;,&quot;metrics&quot;:&quot;OK&quot;,&quot;transaction&quot;:&quot;OK&quot;,&quot;appfabric&quot;:&quot;OK&quot;,&quot;metadata.service&quot;:&quot;OK&quot;,</span>
<span class="go"> &quot;streams&quot;:&quot;OK&quot;,&quot;explore.service&quot;:&quot;OK&quot;,&quot;log.saver&quot;:&quot;OK&quot;,&quot;metrics.processor&quot;:&quot;OK&quot;}</span>
</pre></div>
</div>
</li>
</ul>
<ul class="simple">
<li>Check that the CDAP UI is accessible (by default, the URL will be
<code class="docutils literal notranslate"><span class="pre">http://&lt;host&gt;:11011</span></code> where <code class="docutils literal notranslate"><span class="pre">&lt;host&gt;</span></code> is the IP address of one of the machines where you
installed the packages and started the services).</li>
</ul>
</div>
<div class="section" id="the-cdap-ui-is-showing-a-message-namespace-cannot-be-found">
<h2>The CDAP UI is showing a message “namespace cannot be found”.<a class="headerlink" href="#the-cdap-ui-is-showing-a-message-namespace-cannot-be-found" title="Permalink to this headline">🔗</a></h2>
<p>This is indicative that the UI cannot connect to the CDAP system service containers running in YARN.</p>
<ul class="simple">
<li>First, check if the CDAP Master service container shows as RUNNING in the YARN ResourceManager UI.
The CDAP Master, once it starts, starts the other CDAP system service containers, so if it isn’t running,
the others won’t be able to start or work correctly. It can take several minutes for everything to start up.</li>
<li>If this doesn’t resolve the issue, then it means the CDAP system services were unable to launch.
Ensure <a class="reference internal" href="#faq-installation-startup-memory-core-requirements"><span class="std std-ref">YARN has enough spare memory and vcore capacity</span></a>.
CDAP attempts to launch between 8 and 11 containers, depending on the configuration. Check
the master container (Application Master) logs to see if it was able to launch all containers.</li>
<li>If it was able to launch all containers, then you may need to check the launched container logs for any errors.
The <code class="docutils literal notranslate"><span class="pre">yarn-site.xml</span></code> configuration file determines the container log directory.</li>
<li>Ensure that the CDAP UI can connect to the CDAP Router. Check that the configured
<code class="docutils literal notranslate"><span class="pre">router.server.address</span></code> and <code class="docutils literal notranslate"><span class="pre">router.server.port</span></code> (default 11015) in
<a class="reference external" href="../../admin-manual/installation/packages.html#packages-configuration-options" title="(in Cask Data Application Platform v6.1.1)"><span class="xref std std-ref">cdap-site.xml file</span></a> corresponds with where the CDAP
Router is listening.</li>
</ul>
</div>
<div class="section" id="i-don-t-see-the-cdap-master-service-on-yarn">
<h2>I don’t see the CDAP Master service on YARN.<a class="headerlink" href="#i-don-t-see-the-cdap-master-service-on-yarn" title="Permalink to this headline">🔗</a></h2>
<ul class="simple">
<li>Ensure that the node where CDAP is running has a properly configured YARN client.
Can you log into the cluster at <code class="docutils literal notranslate"><span class="pre">http://&lt;host&gt;:8088</span></code> and access the YARN Resource Manager webapp?</li>
<li>Ensure <a class="reference internal" href="#faq-installation-startup-memory-core-requirements"><span class="std std-ref">YARN has enough memory and vcore capacity</span></a>.</li>
<li>Is the router address properly configured (<code class="docutils literal notranslate"><span class="pre">router.server.address</span></code> and <code class="docutils literal notranslate"><span class="pre">router.server.port</span></code>
(default 11015) in <a class="reference external" href="../../admin-manual/installation/packages.html#packages-configuration-options" title="(in Cask Data Application Platform v6.1.1)"><span class="xref std std-ref">cdap-site.xml file</span></a>) and the boxes using it?</li>
<li>Check that the classpath used includes the YARN configuration in it.</li>
</ul>
</div>
<div class="section" id="yarn-application-shows-accepted-for-some-time-but-then-fails">
<h2>YARN Application shows ACCEPTED for some time but then fails.<a class="headerlink" href="#yarn-application-shows-accepted-for-some-time-but-then-fails" title="Permalink to this headline">🔗</a></h2>
<p>It’s possible that YARN can’t extract the .JARs to the <code class="docutils literal notranslate"><span class="pre">/tmp</span></code>,
either due to a lack of disk space or permissions.</p>
<p class="rubric">Installation: General</p>
</div>
<div class="section" id="the-cdap-master-log-shows-permissions-issues">
<h2>The CDAP Master log shows permissions issues.<a class="headerlink" href="#the-cdap-master-log-shows-permissions-issues" title="Permalink to this headline">🔗</a></h2>
<p>Ensure that <code class="docutils literal notranslate"><span class="pre">hdfs:///${hdfs.namespace}</span></code> and <code class="docutils literal notranslate"><span class="pre">hdfs:///user/${hdfs.user}</span></code> exist and are owned by <code class="docutils literal notranslate"><span class="pre">${hdfs.user}</span></code>.
(<code class="docutils literal notranslate"><span class="pre">hdfs.namespace</span></code> and <code class="docutils literal notranslate"><span class="pre">hdfs.user</span></code> are defined in your installation’s <a class="reference external" href="../../admin-manual/installation/packages.html#packages-configuration-options" title="(in Cask Data Application Platform v6.1.1)"><span class="xref std std-ref">cdap-site.xml file</span></a>.)</p>
<p>In any other cases, the error should show which directory it is attempting to access, such as:</p>
<div class="highlight-console notranslate"><div class="highlight"><pre><span></span><span class="go">2015-10-30 22:14:27,528 - ERROR [ STARTING:...MasterServiceMain$2@452] - master.services failed with exception; restarting with back-off</span>
<span class="go">java.lang.RuntimeException: java.io.IOException: failed to copy bundle from file:/tmp/appMaster.37a86cfd....jar5052.tmp</span>
<span class="go">to hdfs://nameservice/cdap/twill/master.services/b4ce41a5e7e5.../appMaster.37a86cfd-1d88.jar</span>
<span class="go">      at com.google.common.base.Throwables.propagate(Throwables.java:160) ~[com.google.guava.guava-13.0.1.jar:na]</span>
<span class="go">      ...</span>
<span class="go">Caused by: org.apache.hadoop.ipc.RemoteException(org.apache.hadoop.security.AccessControlException):</span>
<span class="go">Permission denied: user=yarn, access=WRITE, inode=&quot;/&quot;:hdfs:supergroup:drwxr-xr-x</span>
<span class="go">at org.apache.hadoop.hdfs.server.namenode.FSPermissionChecker.checkFsPermission(FSPermissionChecker.java:271)</span>
<span class="go">at org.apache.hadoop.hdfs.server.namenode.FSPermissionChecker.check(FSPermissionChecker.java:257)</span>
</pre></div>
</div>
<p>or:</p>
<div class="highlight-console notranslate"><div class="highlight"><pre><span></span><span class="go">Deploy failed: Could not create temporary directory at: /var/tmp/cdap/data/namespaces/phoenix/tmp</span>
</pre></div>
</div>
<p>Don’t hesitate to ask for help at the <a class="reference external" href="https://groups.google.com/d/forum/cdap-user">cdap-user&#64;googlegroups.com</a>.</p>
</div>
<div class="section" id="the-cdap-master-log-shows-an-error-about-the-dataset-service-not-being-found">
<h2>The CDAP Master log shows an error about the dataset service not being found.<a class="headerlink" href="#the-cdap-master-log-shows-an-error-about-the-dataset-service-not-being-found" title="Permalink to this headline">🔗</a></h2>
<p>If you see an error such as:</p>
<div class="highlight-console notranslate"><div class="highlight"><pre><span></span><span class="go">2015-05-15 12:15:53,028 - ERROR [heartbeats-scheduler:c.c.c.d.s.s.MDSStreamMetaStore$1@71]</span>
<span class="go">- Failed to access app.meta table io.cdap.cdap.api.dataset.DatasetManagementException:</span>
<span class="go">Cannot retrieve dataset instance app.meta info, details: Response code: 407,</span>
<span class="go">message:&#39;Proxy Authentication Required&#39;,</span>
<span class="go">body: &#39;&lt;HTML&gt;&lt;HEAD&gt; &lt;TITLE&gt;Access Denied&lt;/TITLE&gt; &lt;/HEAD&gt;</span>
</pre></div>
</div>
<p>According to that log, this error can be caused by a proxy setting. CDAP services
internally makes HTTP requests to each other; one example is the dataset service.
Depending on your proxy and its settings, these requests can end up being sent to the
proxy instead.</p>
<p>One item to check is that your system’s network setting is configured to exclude both
<code class="docutils literal notranslate"><span class="pre">localhost</span></code> and <code class="docutils literal notranslate"><span class="pre">127.0.0.1</span></code> from the proxy routing. If they aren’t, the services will
not be able to communicate with each other, and you’ll see error messages such as these.
You can set a system’s network setting for a proxy by using:</p>
<div class="highlight-console notranslate"><div class="highlight"><pre><span></span><span class="gp">$</span> <span class="nb">export</span> <span class="nv">no_proxy</span><span class="o">=</span><span class="s2">&quot;localhost,127.0.0.1&quot;</span>
</pre></div>
</div>
</div>
<div class="section" id="cdap-services-on-distributed-cdap-aren-t-starting-up-due-to-an-exception-what-should-i-do">
<h2>CDAP services on Distributed CDAP aren’t starting up due to an exception. What should I do?<a class="headerlink" href="#cdap-services-on-distributed-cdap-aren-t-starting-up-due-to-an-exception-what-should-i-do" title="Permalink to this headline">🔗</a></h2>
<p>If the CDAP services on a Distributed CDAP installation wouldn’t start up due to a
<code class="docutils literal notranslate"><span class="pre">java.lang.ClassNotFoundException</span></code>, you will see errors in the logs. You will find in
the logs for <code class="docutils literal notranslate"><span class="pre">cdap-master</span></code> under <code class="docutils literal notranslate"><span class="pre">/var/log/cdap/master*.log</span></code> errors such as these:</p>
<div class="highlight-console notranslate"><div class="highlight"><pre><span></span><span class="go">&quot;Exception in thread &quot;main&quot; java.lang.NoClassDefFoundError:</span>
<span class="go">  io.cdap.cdap.data.runtime.main.MasterServiceMain</span>
<span class="go">    at gnu.java.lang.MainThread.run(libgcj.so.10)&quot;</span>
</pre></div>
</div>
<p>Things to check as possible solutions:</p>
<ol class="arabic">
<li><p class="first">Check if the JDK being used is <a class="reference external" href="../../admin-manual/system-requirements.html#admin-manual-install-java-runtime" title="(in Cask Data Application Platform v6.1.1)"><span class="xref std std-ref">supported by CDAP</span></a>:</p>
<div class="highlight-console notranslate"><div class="highlight"><pre><span></span><span class="gp">$</span> java -version
</pre></div>
</div>
</li>
<li><p class="first">Check if the CDAP user is using a <a class="reference external" href="../../admin-manual/system-requirements.html#admin-manual-install-java-runtime" title="(in Cask Data Application Platform v6.1.1)"><span class="xref std std-ref">correct version of the JDK</span></a>:</p>
<div class="highlight-console notranslate"><div class="highlight"><pre><span></span><span class="gp">$</span> sudo su - &lt;cdap-user&gt;
<span class="gp">$</span> java -version
</pre></div>
</div>
</li>
<li><p class="first">Run this command to see if all the CDAP classpaths are included:</p>
<div class="highlight-console notranslate"><div class="highlight"><pre><span></span><span class="gp">$</span> /opt/cdap/master/bin/cdap classpath <span class="p">|</span> tr <span class="s1">&#39;:&#39;</span> <span class="s1">&#39;\n&#39;</span>
</pre></div>
</div>
<p>Expect to see (where <em>&lt;version&gt;</em> is the appropriate <code class="docutils literal notranslate"><span class="pre">hbase-compat</span></code> version):</p>
<div class="highlight-console notranslate"><div class="highlight"><pre><span></span><span class="go">/etc/cdap/conf/</span>
<span class="go">/opt/cdap/hbase-compat-&lt;version&gt;/lib/*</span>
<span class="go">/opt/cdap/master/conf/</span>
<span class="go">/opt/cdap/master/lib/*</span>
</pre></div>
</div>
<p>If the classpath is incorrect (in general, the <code class="docutils literal notranslate"><span class="pre">hbase-compat-&lt;version&gt;/lib/*</span></code> and
<code class="docutils literal notranslate"><span class="pre">cdap/master/lib/*</span></code> entries must precede any other paths that contain JARs or classes
such as the HBase classpath), review the <a class="reference external" href="../../admin-manual/installation/index.html#installation-index" title="(in Cask Data Application Platform v6.1.1)"><span class="xref std std-ref">installation instructions</span></a> and correct.</p>
</li>
</ol>
</div>
<div class="section" id="we-aren-t-seeing-any-metrics-or-logs-what-should-we-do">
<h2>We aren’t seeing any Metrics or Logs. What should we do?<a class="headerlink" href="#we-aren-t-seeing-any-metrics-or-logs-what-should-we-do" title="Permalink to this headline">🔗</a></h2>
<p>Check that:</p>
<ul class="simple">
<li><code class="docutils literal notranslate"><span class="pre">cdap_kafka</span></code> is running and listening on the configured port (9092 by default);</li>
<li>All nodes of the cluster can successfully connect to the <code class="docutils literal notranslate"><span class="pre">cdap_kafka</span></code> host/port;
use telnet or similar to verify connectivity;</li>
<li>The <em>Kafka</em> server is running;</li>
<li>The local <code class="docutils literal notranslate"><span class="pre">kafka.logs.dir</span></code> exists and has full permissions for the <code class="docutils literal notranslate"><span class="pre">cdap</span></code> user; and</li>
<li>For systems with high availability (HA), on the initial startup the number of available
seed brokers must be greater than or equal to the <em>Kafka</em> default replication factor.</li>
</ul>
<p>In a two-box HA setup with a replication factor of two, if one box fails to startup,
metrics will not show up though the application will still run:</p>
<div class="highlight-console notranslate"><div class="highlight"><pre><span></span><span class="go">[2013-10-10 20:48:46,160] ERROR [KafkaApi-1511941310]</span>
<span class="go">      Error while retrieving topic metadata (kafka.server.KafkaApis)</span>
<span class="go">      kafka.admin.AdministrationException:</span>
<span class="go">             replication factor: 2 larger than available brokers: 1</span>
</pre></div>
</div>
<p>As a last resort, <code class="docutils literal notranslate"><span class="pre">cdap_kafka</span></code> can be reset by stopping CDAP (including <code class="docutils literal notranslate"><span class="pre">cdap_kafka</span></code>),
removing the Kafka <code class="docutils literal notranslate"><span class="pre">znode</span></code> (from within ZooKeeper use <code class="docutils literal notranslate"><span class="pre">rmr</span> <span class="pre">/${cdap.namespace}/kafka</span></code>)
and restarting CDAP.</p>
</div>
<div class="section" id="only-the-first-flowlet-of-our-cdap-application-is-showing-activity">
<h2>Only the first flowlet of our CDAP application is showing activity.<a class="headerlink" href="#only-the-first-flowlet-of-our-cdap-application-is-showing-activity" title="Permalink to this headline">🔗</a></h2>
<p>Check that YARN has the capacity to start any of the remaining containers.</p>
</div>
<div class="section" id="log-saver-process-throws-an-out-of-memory-error-the-cdap-ui-shows-service-not-ok">
<h2>Log Saver Process throws an Out-of-Memory Error; the CDAP UI shows service “Not OK”<a class="headerlink" href="#log-saver-process-throws-an-out-of-memory-error-the-cdap-ui-shows-service-not-ok" title="Permalink to this headline">🔗</a></h2>
<p>The CDAP Log Saver uses an internal buffer that may overflow and result in Out-of-Memory
Errors when applications create excessive amounts of logs. One symptom of this is that the CDAP
UI <em>Services Explorer</em> shows the <code class="docutils literal notranslate"><span class="pre">log.saver</span></code> service as not <em>OK</em>, in addition to seeing error
messages in the logs.</p>
<p>By default, the Log Saver process is limited to 1GB of memory and the buffer keeps eight buckets of events
in-memory. Each event bucket contains logs generated for one second. When it is expected that logs exceeding
these settings will be produced—for example, greater than 1GB of logs generated in eight seconds—increase
the memory allocated to the Log Saver or increase the number of Log Saver instances. If the cluster has
limited memory or containers available, you can choose instead to decrease the number of in-memory event buckets.
However, decreasing the number of in-memory buckets may lead to out-of-order log events.</p>
<p>In the <code class="docutils literal notranslate"><span class="pre">cdap-site.xml</span></code>, you can:</p>
<ul class="simple">
<li>Increase the memory by adjusting <code class="docutils literal notranslate"><span class="pre">log.saver.container.memory.mb</span></code>;</li>
<li>Increase the number of Log Saver instances using <code class="docutils literal notranslate"><span class="pre">log.saver.container.num.cores</span></code>; and</li>
<li>Adjust the number of in-memory log buckets <code class="docutils literal notranslate"><span class="pre">log.saver.event.max.inmemory.buckets</span></code>.</li>
</ul>
<p>See the <code class="docutils literal notranslate"><span class="pre">log.saver</span></code> parameter section of the <a class="reference external" href="../../admin-manual/appendices/cdap-site.html#appendix-cdap-site-xml" title="(in Cask Data Application Platform v6.1.1)"><span class="xref std std-ref">Appendix cdap-site.xml</span></a> for a list of these configuration parameters and their
values that can be adjusted.</p>
<p class="rubric">Upgrading CDAP</p>
</div>
<div class="section" id="can-a-cdap-installation-be-upgraded-more-than-one-version">
<h2>Can a CDAP installation be upgraded more than one version?<a class="headerlink" href="#can-a-cdap-installation-be-upgraded-more-than-one-version" title="Permalink to this headline">🔗</a></h2>
<p>In general, no. (The exception is an upgrade from 2.8.x to 3.0.x.)
This table lists the upgrade paths available for different CDAP versions:</p>
<table border="1" class="docutils">
<colgroup>
<col width="30%" />
<col width="70%" />
</colgroup>
<thead valign="bottom">
<tr class="row-odd"><th class="head">Version</th>
<th class="head">Upgrade Directly To</th>
</tr>
</thead>
<tbody valign="top">
<tr class="row-even"><td>3.2.x</td>
<td>3.3.x</td>
</tr>
<tr class="row-odd"><td>3.1.x</td>
<td>3.2.x</td>
</tr>
<tr class="row-even"><td>3.0.x</td>
<td>3.1.x</td>
</tr>
<tr class="row-odd"><td>2.8.x</td>
<td>3.0.x</td>
</tr>
<tr class="row-even"><td>2.6.3</td>
<td>2.8.2</td>
</tr>
</tbody>
</table>
<p>If you are doing a new installation, we recommend using the current version of CDAP.</p>
</div>
<div class="section" id="i-missed-doing-a-step-while-upgrading-how-do-i-fix-my-system">
<span id="faqs-cloudera-troubleshooting-upgrade-cdh"></span><h2>I missed doing a step while upgrading; how do I fix my system?<a class="headerlink" href="#i-missed-doing-a-step-while-upgrading-how-do-i-fix-my-system" title="Permalink to this headline">🔗</a></h2>
<p>If you miss a step in the upgrade process and something goes wrong, it’s possible that the
tables will get re-enabled before the coprocessors are upgraded. This could cause the
regionservers to abort and may make it very difficult to get the cluster back to a stable
state where the tables can be disabled again and complete the upgrade process.</p>
<p>In that case, set this configuration property in <code class="docutils literal notranslate"><span class="pre">hbase-site.xml</span></code>:</p>
<div class="highlight-xml notranslate"><div class="highlight"><pre><span></span><span class="nt">&lt;property&gt;</span>
  <span class="nt">&lt;name&gt;</span>hbase.coprocessor.abortonerror<span class="nt">&lt;/name&gt;</span>
  <span class="nt">&lt;value&gt;</span>false<span class="nt">&lt;/value&gt;</span>
<span class="nt">&lt;/property&gt;</span>
</pre></div>
</div>
<p>and restart the HBase regionservers. This will allow the regionservers to start up
despite the coprocessor version mismatch. At this point, you should be able to run through
the upgrade steps successfully.</p>
<p>At the end, remove the entry for <code class="docutils literal notranslate"><span class="pre">hbase.coprocessor.abortonerror</span></code> in order to ensure
that data correctness is maintained.</p>
<p class="rubric">Ask the CDAP Community for assistance</p>
<p>You can post a question at the <a class="reference external" href="https://groups.google.com/d/forum/cdap-user">cdap-user&#64;googlegroups.com</a>.</p>
<p>The <em>cdap-user</em> mailing list is primarily for users using the product to develop
applications. You can expect questions from users, release announcements, and any other
discussions that we think will be helpful to the users.</p>
</div>
</div>

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